Ewing sarcoma arising in colon and ovary––Two rare sites of presentation

Ewing sarcoma is a rare aggressive malignant round cell tumor, primarily presenting in bone and soft tissues. This study presents two cases of this tumor in unusual locations, one in right colon which presented with intussusception and other in ovary which presented clinically as carcinoma ovary. Both the cases showed histomorphology of primitive round cell tumor with characteristic immunohistochemical profile and was confirmed on molecular analysis. We aim to highlight the importance of considering Ewing sarcoma in the differential diagnoses in these locations as they have dismal prognosis with no standard treatment modality.

Tumor neuroectodérmico primitivo primario de ovario

El tumor neuroectodérmico primitivo del ovario es un sarcoma de tejido blando de células redondas pequeñas, raro y agresivo, de origen neural que generalmente se asocia con una alta morbilidad y mortalidad. La inmunohistoquímica es un complemento útil en el diagnóstico diferencial. Se describe un caso de tumor neuroectodérmico primitivo del ovario en paciente nulípara de 21 años que refería dolor y aumento de la circunferencia abdominal. La ecografía mostró tumoración de contenido heterogéneo sólido-quística que aparentemente se originaba del anexo izquierdo. La resonancia magnética confirmó la presencia de tumoración que se extendía hacia la fosa iliaca izquierda sin afectación de órganos locales ni metástasis regionales o a distancia. Los marcadores tumorales estaban todos dentro del rango normal. Durante la laparotomía se observó tumoración de ovario izquierdo con ovario derecho normal. Se realizó salpingoforectomía izquierda debido al tamaño del tumor, resección en cuña de ovario derecho, linfadenectomía pélvica y omentectomía. El examen histopatológico reveló tumor compuesto por láminas de células redondas. Las células tumorales fueron positivas para cromogranina A, sinatrofisina, vimentina y enolasa específica de neuronas, lo que confirmó el diagnóstico de tumor neuroendocrino primitivo de ovario izquierdo, que se originaba de teratoma quístico inmaduro. La paciente rechazó la quimioterapia postoperatoria.

Primitive neuroectodermal tumor of the ovary is a rare and aggressive small round cell soft tissue sarcoma of neural origin that is usually associated with high morbidity and mortality. Immunohistochemistry is a useful adjunct in the differential diagnosis. We describe a case of a primitive neuroectodermal tumor of the ovary in a 21-yearold nulliparous patient who reported pain and increased abdominal circumference. Ultrasonography showed a solid-cystic heterogeneous tumor apparently originating from the left adnexa. Magnetic resonance imaging confirmed the presence of a tumor extending into the left iliac fossa without local organ involvement or regional or distant metastases. Tumor markers were all within the normal range. During laparotomy, a left ovarian tumor was observed with a normal right ovary. Left salpingo-oophorectomy was performed due the size of the tumor, right ovarian wedge resection, pelvic lymphadenectomy and omentectomy. Histopathologic examination revealed tumor composed of sheets of round cells. The tumor cells were positive for chromogranin A, synaptophysin, vimentin and neuron-specific enolase, which confirmed the diagnosis of a primitive neuroendocrine tumor of the left ovary originating from immature cystic teratoma. The patient refused postoperative chemotherapy.

Cervical Primary Ewing's Sarcoma:Report of One Case / 中国医学科学院学报

Ewing's sarcoma in the cervix is characterized by extremely rare occurrence,high degree of malignancy,and rapid progression.The diagnosis of this disease is based on pathology and immunohistochemistry. The main image of the case reported in this paper showed the cervical cyst with solid mass,large volume,and uneven density and signal,and the solid part can be strengthened in enhanced scanning.Because of the rapid growth,the lesion is prone to liquefaction necrosis and bleeding.Since the metastasis occurs early,timely diagnosis is essential.

Peripheral primitive neuroectodermal tumor of the mandible: a case report and literature review / 口腔疾病防治

Objective@# To explore the clinical, imaging and pathological characteristics of mandibular peripheral primitive neuroectodermal tumors, and to review relevant literature to improve the understanding and diagnosis of pPNET in mandible.@* Methods@# The clinical and imaging features, pathological examination, treatment and prognosis of a case of mandibular pPNET diagnosed and treated at the First Affiliated Hospital of Xinjiang Medical University were observed, and analyzed a literature review. @* Results @#The patient′s clinical manifestations were an enlarged mass of the mandible, hard texture, unclear borders, involving loose teeth, and numbness of the lower lip; CT and MRI showed osteolytic and aggressive growth patterns. The mandibular tumor was resected and the mandibular partial truncated resection was performed on the titanium plate. Postoperative pathological sections showed small round cell tumors under HE staining and Vimentin and Fli-1 were positive, and the pathological diagnosis was pPNET. The patient did not undergo chemoradiotherapy after surgery and died of tumor recurrence after 9 months of follow-up. A review of the relevant literature revealed that pPNETs are a group of small round cell tumors, which are more common in children and adolescents. pPNETs have a high degree of malignancy, a short course of disease and fast metastasis. The main route of metastasis is through the blood circulation. Most patients die within 2 years, the 3-year survival rate is only 30%, and the 5-year survival rate is less than 10%. Imaging is generally nonspecific; therefore, pPNETs are easily misdiagnosed. The final tumor type is determined by pathological HE staining and immunohistochemical characteristics. Current treatment methods are mainly complete surgical resection combined with postoperative radiotherapy and chemotherapy, but it is critical to provide individualized treatment to patients when necessary.@*Conclusion@# pPNETs have a high degree of malignancy, easy recurrence and poor prognosis, so early diagnosis and treatment are extremely important.

Imaging Findings and Pathological Characteristics of Primitive Neuroectodermal Tumor / 中国医科大学学报

Objective To investigate the imaging findings and pathological characterislics of primitive neuroectodennal tumor (PNET). Meth-ods Imaging data of 22 cases of PN ET confirmed by pathology were retrospectively analyzed. Results There were 5 cases of central PNET, which were round or lobulated masses, 4 cases with cystic degeneration, 1 case with necrosis, and 4 cases with mild peritu moraledema. Magnetic resonance imaging (MRI) revealed isointensity or slightlyhy pointensity on Tl-and hyperin tensity on T2-weighted imag-es, and marked heterogeneous enhancement. There were 17 cases of peripheral PNET, which were mostly large lobulated soft tissue mass-es, 7cases with cystic degeneration, 3 cases with necrosis, and 8 cases with boned estructio n. Computed tomography (CT) scan showed iso-lowd ensity. MRI revealed isointensity or slightly hypointensity on Tl-and heterogeneous hypeiintensityon T2-weighted images, and marked heterogeneous enhancement. Hematoxylin-eosin staining showed Homer-Wright rosette arrangement of the tumor cells in 13 cases. Immunohistochemical staining revealed expression of CD99 (17/22), CD56 (16/18), Ki-67 (22/22), and vimentin (22/22) by the tumorcells. Conclusion MRI and CT findings of PNET are characteristic and helpful in differential diagnosis of the disease. CD99 is of signif-icant value as a diagnostic biomarker and in the classification of PNET.

Clinical analysis of 18 cases of breast primitive neuroectodermal tumor / 中华内分泌外科杂志

Objective To investigate the clinical pathological characteristics and prognosis of primitive neuroectodermal tumor (PNET) of breast.Methods Patients with breast PNET were retrieved from CNKI,Pubmed,Europe PMC and other databases from Jan.1980 to Dec.2016.The clinical data of one patient with breast PNET in our hospital were analyzed retrospectively.Results 18 cases had painless,rapid growth mass as the main clinical features.The pathological morphology showed small round cell tumors,PAS staining positive.Immunohistochemistry CD99 and Fli-1 characteristic expression were the main indexes for the diagnosis of breast PNET.The positive expression of Vimentin,NSE,Syn and negative expression of CK,EMA,Desmin,CgA,LCA,S-100 also played an important role in the diagnosis of breast PNET.The positive expression of genetic marker EWSRI was the golden standard for diagnosis of breast PNET.The size of the tumor,surgical treatment,lymph node metastasis,distant metastasis and chemotherapy were the important factors that affect the prognosis of the PNET.The survival rates of 1 and 3 years were 71.4％ and 33.3％ respectively.Conclusions Breast PNET is a rare tumor with poor prognosis,and its diagnosis is highly dependent on pathology.Surgery can significantly improve the prognosis of the patients.Surgery should be the main treatment,combined with radiotherapy and chemotherapy.The current study does not show evidence of effectiveness in terms of endocrine or targeted drug therapy for breast PNET patients.

Primary primitive neuroectodermal tumor of the kidney

Renal primitive neuroectodermal tumor (PNET) is a rare entity. It should be differentiated from other primary renal malignancies. The differentiation of the malignant small round cell tumors may be challenging; however, it is essential for better management of the patient. We report a 45-year-old male having complaints of pain in the abdomen, hematuria, and mass in the abdomen for 6 months. Abdominal and pelvic sonography finding showed cystic-solid, right renal mass suggestive of malignancy. On histopathology diagnosed as malignant small round blue cell tumor suggestive of primitive neuroectodermal tumor. On immunohistochemistry, CD99 positivity confirmed the diagnosis of primary PNET of the kidney. We are presenting this case for its rarity, clinical presentation, and pathological findings.

A mesenteric primary peripheral Ewing's sarcoma/primitive neuroectodermal tumor with molecular cytogenetic analysis: Report of a rare case and review of literature

Rare cases of Ewing's sarcoma/primitive neuroectodermal tumors (EWS/PNETs) arising from mesenteric tissue have been reported. This report describes an EWS/PNET in a 25-year-old woman who presented with abdominal pain lasting 3 days. Radiologic evaluation revealed a 9 cm × 6 cm homogeneous mass in the lower abdomen with homogeneous enhancement and invasion of the ileum. Surgical resection was completed during exploratory laparotomy. Immunohistochemically, the tumor cells revealed CD99, friend leukemia virus integration-1 and NKX2.2 (NK2 Homeobox 2, a protein coding gene) and subsequently showed EWSR1 rearrangement. The histological feature, immunohistochemical results and genetic fluorescence in situ hybridization analysis of this case were confirming the diagnosis of EWS/PNET. Adjuvant chemotherapy was suggested, but the patient was lost to follow-up.

Survival and prognostic factors analysis of primitive neuroectodermal tumor / 中华肿瘤杂志

Objective@#To investigate the clinical features and prognosis of primitive neuroectodermal tumor (PNET).@*Methods@#The clinical data of 99 patients with PNET from February 1, 1998 to February 1, 2017 were retrospectively analyzed. Univariate analysis was performed using Kaplan-Meier and Log rank test. Multiviate Cox regression was applied to analyzed independent prognostic factor for patient survival.@*Results@#Among the 99 patients, 81 were peripheral PNET(pPNET) and 18 were central PNET (cPNET) . Biopsy was performed exclusively in 16 cases, with R0 resection in 61 cases, with R1 resection in 4 cases, and with R2 resection in 18 cases. Twelve patients underwent surgery only, nine had chemotherapy only, and one received radiotherapy only. There were 72 patients who had combined treatment including chemotherapy, and 48 patients had combined therapy including radiotherapy. The one-year, three-year and five-year overall survival(OS) rates of the 99 PNET patients were 79.2%, 63.9% and 56.1% respectively, and median OS time was 14.0 months. The one-year, three-year and five-year progression free survival (PFS) rates of these patients were 42.7%, 25.7% and 19.8% respectively, and median PFS time was 8.0 months. The univariate analysis revealed that lymph node metastasis, surgical resection, numbers of cycles of chemotherapy and radiotherapy dose were the main factors affecting the OS (all P<0.05). Gender, age, lymph node metastasis, staging, and chemotherapy cycles were related to PFS in PNET patients (P<0.05). Multivariate analysis showed that the degree of surgical resection, chemotherapy cycle, and radiotherapy dosage were independent influencing factors of OS in PNET patients (risk ratio=1.856, 0.398, and 0.408, respectively, all P<0.05), and gender was an independent factor influencing PFS in PNET patients (risk ratio=0.494, P<0.05).@*Conclusions@#Comprehensive therapy is the main therapy for PNET patients. The surgical resection, cycles of chemotherapy and radiotherapy dosage are independent prognostic factors for patient′s OS.

CT manifestations of primitive neuroectodermal tumor of adrenal gland / 实用放射学杂志

Objective To explore the CT manifestations of primitive neuroectodermal tumor (PNET) of adrenal gland,aiming to increase the cognition on this disease.Methods The CT manifestations of 7 patients who were pathologically diagnosed with adrenal gland PNET were analyzed retrospectively.Results The age of patients was 24-63 years old,with average age of (47.6±13.7) years,including 6 females and 1 male.Location of PNET:4 in left adrenal gland and 3 in right adrenal gland.Clinical manifestations:3 cases had upper abdominal distension,2 cases suffered from pain of waist and back,1 case was discovered in physical examination and another 1 had fever.No abnormality was found in laboratory and endocrinological examinations.After operation,4 cases had recurrence and 2 had distant metastasis.During follow-up,6 patients died and only 1 still alive.CT showed that the tumor,whose maximum diameter was 10.1-19.4 cm,was elliptic or lobulated in shape.The tumor was clear in boundary in 2 patients,but was unclear in boundary and involved adjacent organs in 5 patients.The plain scanning showed equidensity or slightly low density,complicated with necrosis and cystic lesions without calcification.The enhanced scanning suggested progressive uneven enhancement,with multiple interatrial septum-like changes and latticed enhancement inside.Conclusion CT manifestations of adrenal gland PNET can prompt the diagnosis,pathological examination is still required for confirmation.CT can accurately describe the internal structures,adjacent relationship and the metastasis of tumors.

Supratentorial primitive neutoectodermal tumors in adults:imaging findings and analysis on misdiagnosis / 实用放射学杂志

Objective To investigate the CT and MRI features of supratentorial primitive neuroectodermal tumors (sPNET)in adults,and to analyze the reasons of misdiagnosis.Methods The CT and MRI features of 1 5 patients with sPNET confirmed by pathology were analyzed retrospective.13 of 15 patients were underwent plain and contrast enhanced MRI,4 patients were also performed CT scan and the other 2 patients were underwent CT plain scan only.Results Nine of 1 5 lesions were located in the temporal and/or frontal lobe,with clear margin in 12 lesions,and mild to moderate peritumoral was noted in most cases.The solid portion of the lesions were hyperdense on CT,isointense or slightly hypointense on T1WI,and isointense or hyperintense on T2WI compared to the gray matter.Calcification (2/6),necrosis or cystic degeneration(1 3/1 5),hemorrhage (8/1 5)and flow void signal (1 1/1 3)were seen.Twelve lesions showed significantly heterogeneous enhancement and 7 lesions showed irregular ring-enhancement.The solid parts in 5 lesions showed hyperintensity on diffusion-weighted imaging. Preoperatively,the lesions were misdiagnosed as glioma in 10 cases,ependymoma in 2 cases,meningioma in 1 case and germ cell tumor in 1 case, respectively;and 1 case was not diagnosed definitely.Conclusion Supratentorial PNET in adults has characteristic CT and MRI features,and the main reasons accounting for misdiagnosis are its extraordinary low incidence and that radiologists do no master its imaging features.

Pediatric Ewing's Sarcoma/Primitive Neuroectodermal Tumor (ES/PNET) Developed in the Small Intestine: A Case Report / 임상소아혈액종양

Ewing sarcoma/primitive neuroectodermal tumors (ES/PNET) are a group of malignant tumors with varying degrees of neuroectodermal differentiation. Although it may develop in any organs, ES/PNET originating from small intestine is exceedingly rare. We experienced a 9-year-old girl presenting with abdominal pain, melena, and iron deficiency anemia. Imaging work-up showed multiple masses in the small bowel and omentum with disseminated peritoneal seeding nodules, indicating lymphoma as the most likely diagnosis. Pathological reports from explorative diagnostic laparoscopic biopsy showed tumors comprising small round cells with CD99 expression and EWS-FLI1 translocation leading to the diagnosis of ES/PNET. Tumor burden decreased gradually during five consecutive cycles of systemic chemotherapy. The patient received segmental resection of jejunum, followed by adjuvant chemotherapy. This is the first pediatric case of ES/PNET found in small intestine in Korea.

The treatment and prognosis of peripheral primitive neuroectodermal tumor / 中华肿瘤杂志

Objective@#To evaluate the treatment and prognosis of peripheral primitive neuroectodermal tumor (pPNET).@*Methods@#From March 2006 to April 2015, 47 patients with pPNET who had undergone chemotherapy in our hospital were enrolled. The clinical data and survival information of these patients were collected and interpreted retrospectively to analyze the effect of each treatment on the survival of patients.@*Results@#The median overall survival (OS) for whole group was 23.5 months, and 5-year survival rate was 33.8%. In the patients who underwent radical surgery, the median OS was 70.4 months, the 5-year survival rate was 54.4%, the median disease-free survival (DFS) was 23.1months, and 5-year DFS rate was 34.4%. Sixteen patients had recurrences or metastasis after surgery. Eighty-one percent of them (13/16) occurred within 2 years after surgery. The difference of median OS between patients who got adjuvant chemotherapy and those who did not was statistically significant (P=0.04). But the difference of median PFS between these two groups was not statistically significant (P=0.057). There was no statistically significant difference for median OS (P=0.619) and median DFS (P=0.191) between patients who got adjuvant radiotherapy and those who did not. The recurrence rate between these two groups was not statistically significant (P=0.40). The median OS and PFS for 34 patients who received first-line palliative chemotherapy was 10.7 months and 3.2 months. 1-year and 2-year survival rates were 48.0% and 17.8%. The response rate and clinical benefit rate for first-line chemotherapy was 53.1% and 75.0%. The median PFS and OS for patients who received platinum-based regimens were 3.3 months and 14.5 months. The median PFS and OS for patients who got non-platinum regimens were 2.7 months and 10.3 months. There was no significant difference of PFS and OS between platinum-based and non-platinum regimens. Palliative surgery and radiotherapy did not improve the OS of pPNET this cohort.@*Conclusions@#Comprehensive treatment including chemotherapy, radiotherapy and surgery is the standard treatment model for early pPNET patients. Adjuvant chemotherapy significantly improved the overall survival of early pPNET patients. Chemotherapy is the main treatment for patients with advanced pPNET. Platinum-based chemotherapy seem to be a good option.

Imaging findings and differential diagnosis of central nervous system primitive neuroectodermal tumors / 实用放射学杂志

Objective To investigate the CT,MRI features and differential diagnosis of central nervous system primitive neuroec-todermal tumors (cPNET).Methods The CT and MRI findings of 1 5 cases with cPNET proved by pathology were analyzed retro-spectively,and we summarized the imaging features and differential diagnosis.Results For this group,the average age was (8.82± 2.53)and the male to female ratio was 9 ︰6.All lesions located in supratentorial region,which had relatively large volume (average diameter of 6.3 cm),cystic necrosis (12/15),and no or mild peritumoral edema.cPNET showed isodensity,slight hyperdensity or slight hypodensity on CT plain scan,and demonstrated uniform or inhomogeneous enhancement.On MRI plain scan,solid part showed isointensity or slight hypointensity signal on T1 WI,isointensity or slight hyperintensity signal on T2 WI,hyperintensity sig-nal on DWI(12/15),isointensity(9/15)or slightly hyperintensity signal on FLAIR,and showed obvious uniform,honeycombed or irregular enhancement after enhanced scan,no enhancement in cystic necrosis.Conclusion cPNET have certain characteristics,inclu-ding the lower onset age,relatively large volume with well-defined edge and no or mild peritumoral edema,hyperintensity signal on DWI,isointensity signal on FLAIR.

Pediatric Ewing's Sarcoma/Primitive Neuroectodermal Tumor (ES/PNET) Developed in the Small Intestine: A Case Report / 임상소아혈액종양

Ewing sarcoma/primitive neuroectodermal tumors (ES/PNET) are a group of malignant tumors with varying degrees of neuroectodermal differentiation. Although it may develop in any organs, ES/PNET originating from small intestine is exceedingly rare. We experienced a 9-year-old girl presenting with abdominal pain, melena, and iron deficiency anemia. Imaging work-up showed multiple masses in the small bowel and omentum with disseminated peritoneal seeding nodules, indicating lymphoma as the most likely diagnosis. Pathological reports from explorative diagnostic laparoscopic biopsy showed tumors comprising small round cells with CD99 expression and EWS-FLI1 translocation leading to the diagnosis of ES/PNET. Tumor burden decreased gradually during five consecutive cycles of systemic chemotherapy. The patient received segmental resection of jejunum, followed by adjuvant chemotherapy. This is the first pediatric case of ES/PNET found in small intestine in Korea.

A prognostic analysis of primitive neuroectodermal tumor for postoperative recurrent patients and a literature review / 解放军医学杂志

Objective To analyze the prognostic factors of primitive neuroectodermal tumor (PNET) for postoperative recurrent patients. Methods Thirty patients admitted from Jun. 2008 to Dec. 2014 and diagnosed as PNET were retrospectively analyzed. Postoperative recurrence happened in all of the patients, of whom 2 received surgery alone, 15 received surgery and chemotherapy without radiotherapy, 3 received surgery and radiotherapy without chemotherapy, and 10 received surgery, radiotherapy and chemotherapy. Kaplan and Meier method was employed to draw the survival curve of the postoperative recurrent PNET patients, and to evaluate the effects of sex, age, radical resection, therapeutic method and relapse-free interval (RFI) on the overall survival (OS). Log-rank method was used to test the significance of differences, and Cox regression was used to analyze all the factors listed above. The literatures related to PNET published domestically and abroad in recent 20 years were reviewed. Results The overall median survival time was 30 months. The OS rates of 1, 3 and 5 years were 80.0%, 44.1% and 20.7%. Local recurrence happened in 26 patients (86.7%), and distant recurrence in 4 patients (13.3%). The overall median RFI was 4 months, and the RFI rates of 6 months, 1 year and 2 years were 33.3%, 16.7% and 6.7%, respectively. The overall median recurrence-free survival (RFS) time was 14 months, and the PRS rates of 1, 3 and 5 years were 60.7%, 16.9% and 8.4%, respectively. The univariate analysis showed that radical resection, radiotherapy and RFI ≥ 6 months predicted significantly better outcome (P=0.033, P=0.006 and P=0.001). The multivariate analysis revealed that radiotherapy and RFI ≥ 6 months were the independent prognosis factors (P=0.047 and P=0.012, respectively). One thousand six hundred and eight cases of recurrent PNET patients were reported abroad since A.D. 2000. The initial recurrence was most often distant only (1089 cases), followed by local only (292 cases) and both distant and local (227 cases). Median RFI ranged from 0.1 to 128 months and the 5-year RFS ranged from 13% to 28%. Major factors influencing RFS included RFI ≥ 24 months, stage of disease at initial diagnosis and high dose treatment. Conclusions The prognosis of PNET patients with postoperative recurrence is very poor. Radiotherapy may have important significance to the PNET patients. RFI <6 months may seriously impact on the OS of PNET patients, but throw no significant influence on the post recurrence survival.

Primary Ewing sarcoma of vulva, confirmed with molecular cytogenetic analysis: A rare case report with diagnostic and treatment implications.

Primary vulvar Ewing sarcoma (ES)/PNET is an uncommonly documented tumor, especially with molecular results. A 10-year-old girl presented with left vulvar swelling, a year ago. Her abdominopelvic ultrasound revealed a 12 cm × 8 cm sized, mixed echogenic blood-fi lled lesion in the left vulva; radiologically considered as a hematoma. Vulvectomy revealed a multinodular grey-brown tumor, microscopically comprising malignant round cells. Immunohistochemically, tumor cells diffusely expressed MIC2/ CD99 and Fli1 and subsequently displayed EWSR1 rearrangement, confi rming diagnosis of ES/PNET. Subsequently, PET-CT scan revealed residual local lesion with lung metastases. The patient was induced on EFT 2001 chemotherapy protocol. Three months after chemotherapy completion, there was no metabolically active disease on PET scan. Four months later, MRI disclosed recurrent primary and metastatic pulmonary lesions. She was planned for scar excision and adjuvant radiotherapy, but unfortunately defaulted further treatment. This forms the eighth case of primary vulvar ES/PNET confi rmed with molecular cytogenetic result, underscoring therapeutic value of objective diagnosis in such cases.

Clinical analysis of children primitive neuroectodermal tumor / 医学研究生学报

Objective Primitive neuroectodermal tumor ( PNET) is a small round cell tumor occurring mostly in children or young adults and categorized into the Ewing sarcoma family of tumors, the purpose of the study was to investigate the clinical features, treatment and prognosis of Children PNET. Methods A retrospective study was performed on clinical data of 13 children with PNET hospitalized in our hospital from March 2010 to Octorber 2014.In order to analyze the clinical effects and prognostic results, statistical analysis was made on their clinical manifestations, CT and ultrasonic results, therapeutic schemes, postoperative pathology and immu-nohistochemical staining results, along with telephone and outpaitient follow-up of average 19 months. Results Of the 13 patients, 4 cases were central nervous system PNET(CNS-PNET) and 9 cases were peripheral PNET(pPNET).The clinical manifestations of the former were headache, vomiting, convolsion, movement disorder or decreased muscle strength, while the latter mainly showed mas-ses and abdominal distention.3 cases with metastasis to lung, lymph nodes and bones respectively showed masses on surface or in cavi-ty in imaging.Homer-Wright pseudorosette textures were found in 12 patients.Immunohistochemical results showed 11 cases with CD99(+), 9 cases with VIM(+) and 8 cases Syn( +).Among 11 patients underwent chemotherapy, 2 cases were lost to follow-up, 7 cases were in stable condition without occurrence and the other 2 cases recurred 4-6 months after chemotherapy.3 of 4 cases with CNS-PNET survived with the sequelae of decreased muscle strength, convolsion and movement disorder.1 case with CNS-PNET and 1 case with pPNET died 7 months and 16 months after diagnosis respectively. Conclusion PNET in children is a very highly malignant tumor with low long-term survival rate.Immunohistochemi-cal examination including CD99 and VIM is of important diagnostic value and CNS-PNET is prone to sequelae.

Clinical and pathological observation on primary pulmonary primitive neuroectodermal tumor / 医学研究生学报

Objective Primitive neuroectodermal tumor (PNET) is a rare malignant small round cell tumor .This paper aimed to study the clinical and pathological features of primary pulmonary primitive neuroectodermal tumor . Methods We collected 2 cases of primary pulmonary PNET to review the clinical and pathological features .Immunohistochemical staining was used to detect immune mark-ers, and fluorescence in situ hybridization (FISH) was applied to detect EWS translocation. Results 2 patients were aged 33 years and 17 years.Microscopically, the tumor cell was composed of single small round cells in diffusion or in distribution of sheets or beams , with scant cytoplasm , oval or spindle-shaped nucleus , high mitotic count .Irregular tumor necrosis scattered in the tumor along with visi-ble rosette structure.Immunohistochemical study showed that the tumor cells were positive for CD 99, FLI-1 and Syn, while CKpan, EMA, Desmin, CgA, TTF1, CD34 were negative.EWS/FLI1 translocations were detected positive in both the cases .2 patients died 7 months and 32 months after operation , respectively . Conclusion Primary pulmonary PNET is rare , so the selection of appropriate im-mune markers (CD99, FLI-1, Syn) and FISH for the detection of EWS translocation helps to improve the accuracy of diagnosis .